Virus infections which attack mammals, including man, are normally contagious afflictions which are capable of causing great human suffering and economic loss. Unfortunately, the discovery of antiviral compounds is far more complicated and difficult than the discovery of antibacterial and antifungal agents. This is due in part, to the close structural similarity of viruses and the structure of certain essential cellular components such as ribonucleic and deoxyribonucleic acids. Nevertheless, numerous non-viral "antiviral agents", i.e. substances "which can produce either a protective or therapeutic effect to the clear detectable advantage of the virus infected host, or any material that can significantly enhance antibody formation, improve antibody activity, improve non-specific resistance, speed convalescence or depress symptoms" [Herrman et al., Proc. Soc. Exptl. Biol. Med., 103, 625 (1960)], have been described in the literature. The list of reported antiviral agents includes, to name a few, interferon and synthetic materials such as amantadine hydrochloride, pyrimidines, biguanides, guanidine, pteridines and methisazone. Because of the rather narrow range of viral infections that can be treated by each of the antiviral agents commercially available at the present time, new synthetic antiviral agents are always welcomed as potentially valuable additions to medical technology.
The cells of mammals produce, in response to virus infection, a substance which enables cells to resist the multiplication of a variety of viruses. The viral-resisting or viral-interfering substances are referred to as "interferons". The interferons are glycoproteins which may differ in their physico-chemical properties, but all exhibit the same biological properties; namely they inhibit a wide range of unrelated viruses, have no toxic or other deleterious effects on cells, and are species-specific (Lockart, Frontiers of Biology, Vol. 2, "Interferons", edited by Finter, W. B. Saunders Co., Philadelphia, 1966, pages 19-20).
No practical, economical method has yet been developed for the preparation of exogenous interferon for routine clinical use against viral infections. An alternative approach to producing interferon has, therefore, been pursued, which comprises administering a non-viral substance which stimulates or induces production of interferon in the cells. The interferon produced in this fashion is referred to as "endogenous" interferon.
Several types of polyamines are known to stimulate interferon production and hence have antiviral activity. They include the polyamines disclosed in U.S. Pat. No. 3,872,171, the xylenediamines disclosed in U.S. Pat. No. 4,034,040, and the phenethanolamine substituted, glycerin-based lipids disclosed in Ser. No. 825,535 allowed Feb. 12, 1979, now U.S. Pat. No. 4,166,132. Other related phenthanolamine substituted, glycerin-based lipids not having antiviral activity are disclosed in Ser. No. 906,260 allowed Feb. 12, 1979, now U.S. Pat. No. 4,173,641.